Table 2.

The examples of biotechnological approaches for steviol glycoside synthesis

Technique		SvGls content	References
Micropropagation		No effect	Kumari and Chandra 2015
		SvGls decrease	Bondarev et al. 2001
Micropropagation + elicitors	alginate and yeast extract	SvGls increase	Bayraktar et al. 2016
Micropropagation + salinity stress	NaCl	Upregulation of several genes encoding key enzymes of the steviol glycoside biosynthetic pathways and SvGls increase	Pandey and Chikara 2015
	NaCl, Na2CO3	SvGls increase	Gupta et al. 2016
	NaCl	SvGls decrease	Fallah et al. 2017
	NaCl	SvGls decrease	Rameeh et al. 2017
	Glycine betaine	SvGls increase	Rameeh et al. 2017
	NaCl	Upregulation of several genes encoding key enzymes of the steviol glycoside biosynthetic pathways	Lucho et al. 2019
Micropropagation + drought stress	Mannitol	Downregulation of several genes encoding key enzymes of the steviol glycoside biosynthetic pathways SvGls decrease	Pandey and Chikara 2015
	Proline	SvGls increase	Gupta et al. 2016
	PEG	SvGls increase	Gupta et al. 2016
Callus and cell suspension culture	plant growth regulators	minor and varied amounts of SvGls	Swanson et al. 1992, Bondarev et al. 2019, 2001 Janarthanam et al. 2010,
Callus and cell suspension culture + salinity stress	NaCl, Na2CO3	SvGls increase	Gupta et al. 2014
Callus and cell suspension culture + drought stress	Proline, PEG	SvGls increase	Gupta et al. 2015
Transformation with Rhizobium rhizogenes, hairy roots production		SvGls not found	Yamazaki and Flores 1991
	Light and dark conditions	Photosynthetically dependent SvGls synthesis and upregulation of UGT85C2 gene	Pandey et al. 2016
	Light stress and osmotic stress	SvGls synthesis	Libik-Konieczny et al. 2020
Transformation with Rhizobium rhizogenes, Agrobacterium Mediated Transient Gene Silencing (AMTS)		Identification of alternative pathway of SvGls biosynthesis	Guleria and Yadav 2013a
Transformation with Rhizobium rhizogenes, hairy roots production and plantlets regeneration		SvGls increase in regenerated plantlets	Sanchéz-Cordova et al. 2019
Genetic modification of microorganisms	Escherichia coli	Reconstruction and expression of kaurene biosynthetic pathway, development of pathways for rebaudioside D synthesis and UDP-glucose recycling, redesigning and reconstruction a steviol-biosynthetic pathway and overproduction of steviol in Escherichia coli	Kong et al. 2015, Wang et al. 2015, Chen et al. 2018, Moon et al. 2002
	Saccharomyces cerevisiae	De novo production of rare steviol glycosides like Reb M or Reb D	Patents of Washington University, University Massachusetts, Evolva cited in: Spakman 2015
Chemical synthesis/enzymatic synthesis		Rebaudiosides A, D and M chemical synthesis, enzymatic modifications to improve the sweet-tasting of SvGls	Qiao et al. 2018, Gerwig et al. 2016